I don't mix it with my foundation, but I use the Le Blanc de Chanel Illuminizing primer and I love it. Very different from any other primer I have tried. Makes my skin look great without any shimmer, but definate "illumination" if that makes sense. Pricey, but I have been very pleased with the relusts.
I use one from Becca on top of my foundation. It's a white luminizer that I just put on my cheeks, bridge of my nose, and browbone. You can really wear it on top of anything; I wear mine over Bare Escentuals mineral makeup and it looks great and makes me look really really healthy and happy.